1. Field of the Invention
The present invention relates to harvesting machines comprising a plurality of sub-assemblies connected together, and to methods of making harvesting machines by connecting sub-assemblies together.
2. Description of the Prior Art
The principle of making large machines such as combine harvesters from a number of pre-formed modules or sub-assemblies is known in the art. For example, it is common practice to construct interchangeable and independent maize and grain headers which can be mounted on a base unit. Dependent on the crop to be harvested, either the grain or the maize header is mounted on the base unit. Furthermore, for transporting the combine harvester on public roads, the header is normally detached from the base unit and placed on a trailer which is then trailed behind the base unit with the header disposed in a generally fore-and-aft direction. The header is an independent sub-assembly which, in the case of grain header, comprises a header trough, cutter means, a feeder auger and a header reel.
It is also known to make the base unit of a combine harvester (the base unit comprising the entire machine minus the header and the straw elevator) of a certain number of sub-assemblies. This is primarily intended to facilitate the construction of the base unit and to reduce manufacturing costs.
However, while the principle of construction using modules or sub-assemblies is already known in the construction of combine harvesters, still further improvements are possible.
In German Pat. No. 1.782.012, it has been proposed to divide the lower portion of the base unit into three sub-assemblies, namely a front sub-assembly with a traction axle, a gearbox and traction wheels; a rear sub-assembly with a rear axle and steerable wheels and a middle sub-assembly with a framework supporting a cleaning device. One disadvantage of this arrangement is that as long as the three sub-assemblies are separate, all three have to be carried through the assembly line of the plant on carriages.
In another arrangement, the base unit comprises a front sub-assembly with threshing means and a front straw walker shaft, and a rear sub-assembly comprising a framework with a rear straw walker shaft mounted therein. Obviously the straw walkers can be mounted on the straw walker shafts only after both the front and rear sub-assemblies are assembled together. This is however very awkward for several reasons, namely;
THE NEED TO ASSEMBLE THE STRAW WALKERS WITH RELATIVELY SMALL TOLERANCES ON THE WALKER SHAFTS,
THE FACT THAT THE STRAW WALKERS ARE ELONGATE STRUCTURES WHICH ARE DIFFICULT TO HANDLE,
THE FACT THAT THE CUMBERSOME STRAW WALKERS REQUIRE TO BE MOUNTED ON THE WALKER SHAFTS IN A RELATIVELY SMALL SPACE,
THE FACT THAT THE STRAW WALKERS REQUIRE TO BE MOUNTED ON THE BASE UNIT AT A CONSIDERABLE HEIGHT ABOVE GROUND LEVEL,
THE FACT THAT THE STRAW WALKERS REQUIRE TO BE MOUNTED AT A LOCATION ABOVE A CLEANING SHOE AND REARWARDLY OF THE THRESHING MEANS, AND THAT AT THE MOMENT OF THE MOUNTING OF THE STRAW WALKERS, THE CLEANING SHOE AND THE TRESHING MEANS ARE ALREADY INSTALLED, SO THAT ACCESS TO THE STRAW WALKER REGION IS DIFFICULT. Moreover, unless special precautions are taken to avoid this, damage might be caused to the cleaning shoe when assembling the straw walkers on the respective shafts.